Bugfix wait in automation (#4984)

homeassistant/components/automation/__init__.py

@@ -166,7 +166,9 @@ def async_setup(hass, config):
         for entity in component.async_extract_from_service(service_call):
             tasks.append(entity.async_trigger(
                 service_call.data.get(ATTR_VARIABLES), True))
-        yield from asyncio.wait(tasks, loop=hass.loop)
+
+        if tasks:
+            yield from asyncio.wait(tasks, loop=hass.loop)
 
     @asyncio.coroutine
     def turn_onoff_service_handler(service_call):
@@ -175,7 +177,9 @@ def async_setup(hass, config):
         method = 'async_{}'.format(service_call.service)
         for entity in component.async_extract_from_service(service_call):
             tasks.append(getattr(entity, method)())
-        yield from asyncio.wait(tasks, loop=hass.loop)
+
+        if tasks:
+            yield from asyncio.wait(tasks, loop=hass.loop)
 
     @asyncio.coroutine
     def toggle_service_handler(service_call):
@@ -186,7 +190,9 @@ def async_setup(hass, config):
                 tasks.append(entity.async_turn_off())
             else:
                 tasks.append(entity.async_turn_on())
-        yield from asyncio.wait(tasks, loop=hass.loop)
+
+        if tasks:
+            yield from asyncio.wait(tasks, loop=hass.loop)
 
     @asyncio.coroutine
     def reload_service_handler(service_call):